drivers/clocksource/h8300_timer8.c

   1 /*
   2  *  linux/arch/h8300/kernel/cpu/timer/timer8.c
   3  *
   4  *  Yoshinori Sato <ysato@users.sourcefoge.jp>
   5  *
   6  *  8bit Timer driver
   7  *
   8  */
   9
  10 #include <linux/errno.h>
  11 #include <linux/kernel.h>
  12 #include <linux/interrupt.h>
  13 #include <linux/init.h>
  14 #include <linux/clockchips.h>
  15 #include <linux/clk.h>
  16 #include <linux/io.h>
  17 #include <linux/of.h>
  18 #include <linux/of_address.h>
  19 #include <linux/of_irq.h>
  20
  21 #define _8TCR   0
  22 #define _8TCSR  2
  23 #define TCORA   4
  24 #define TCORB   6
  25 #define _8TCNT  8
  26
  27 #define CMIEA   6
  28 #define CMFA    6
  29
  30 #define FLAG_STARTED (1 << 3)
  31
  32 #define SCALE 64
  33
  34 #define bset(b, a) iowrite8(ioread8(a) | (1 << (b)), (a))
  35 #define bclr(b, a) iowrite8(ioread8(a) & ~(1 << (b)), (a))
  36
  37 struct timer8_priv {
  38         struct clock_event_device ced;
  39         void __iomem *mapbase;
  40         unsigned long flags;
  41         unsigned int rate;
  42 };
  43
  44 static irqreturn_t timer8_interrupt(int irq, void *dev_id)
  45 {
  46         struct timer8_priv *p = dev_id;
  47
  48         if (clockevent_state_oneshot(&p->ced))
  49                 iowrite16be(0x0000, p->mapbase + _8TCR);
  50
  51         p->ced.event_handler(&p->ced);
  52
  53         bclr(CMFA, p->mapbase + _8TCSR);
  54
  55         return IRQ_HANDLED;
  56 }
  57
  58 static void timer8_set_next(struct timer8_priv *p, unsigned long delta)
  59 {
  60         if (delta >= 0x10000)
  61                 pr_warn("delta out of range\n");
  62         bclr(CMIEA, p->mapbase + _8TCR);
  63         iowrite16be(delta, p->mapbase + TCORA);
  64         iowrite16be(0x0000, p->mapbase + _8TCNT);
  65         bclr(CMFA, p->mapbase + _8TCSR);
  66         bset(CMIEA, p->mapbase + _8TCR);
  67 }
  68
  69 static int timer8_enable(struct timer8_priv *p)
  70 {
  71         iowrite16be(0xffff, p->mapbase + TCORA);
  72         iowrite16be(0x0000, p->mapbase + _8TCNT);
  73         iowrite16be(0x0c02, p->mapbase + _8TCR);
  74
  75         return 0;
  76 }
  77
  78 static int timer8_start(struct timer8_priv *p)
  79 {
  80         int ret;
  81
  82         if ((p->flags & FLAG_STARTED))
  83                 return 0;
  84
  85         ret = timer8_enable(p);
  86         if (!ret)
  87                 p->flags |= FLAG_STARTED;
  88
  89         return ret;
  90 }
  91
  92 static void timer8_stop(struct timer8_priv *p)
  93 {
  94         iowrite16be(0x0000, p->mapbase + _8TCR);
  95 }
  96
  97 static inline struct timer8_priv *ced_to_priv(struct clock_event_device *ced)
  98 {
  99         return container_of(ced, struct timer8_priv, ced);
 100 }
 101
 102 static void timer8_clock_event_start(struct timer8_priv *p, unsigned long delta)
 103 {
 104         struct clock_event_device *ced = &p->ced;
 105
 106         timer8_start(p);
 107
 108         ced->shift = 32;
 109         ced->mult = div_sc(p->rate, NSEC_PER_SEC, ced->shift);
 110         ced->max_delta_ns = clockevent_delta2ns(0xffff, ced);
 111         ced->min_delta_ns = clockevent_delta2ns(0x0001, ced);
 112
 113         timer8_set_next(p, delta);
 114 }
 115
 116 static int timer8_clock_event_shutdown(struct clock_event_device *ced)
 117 {
 118         timer8_stop(ced_to_priv(ced));
 119         return 0;
 120 }
 121
 122 static int timer8_clock_event_periodic(struct clock_event_device *ced)
 123 {
 124         struct timer8_priv *p = ced_to_priv(ced);
 125
 126         pr_info("%s: used for periodic clock events\n", ced->name);
 127         timer8_stop(p);
 128         timer8_clock_event_start(p, (p->rate + HZ/2) / HZ);
 129
 130         return 0;
 131 }
 132
 133 static int timer8_clock_event_oneshot(struct clock_event_device *ced)
 134 {
 135         struct timer8_priv *p = ced_to_priv(ced);
 136
 137         pr_info("%s: used for oneshot clock events\n", ced->name);
 138         timer8_stop(p);
 139         timer8_clock_event_start(p, 0x10000);
 140
 141         return 0;
 142 }
 143
 144 static int timer8_clock_event_next(unsigned long delta,
 145                                    struct clock_event_device *ced)
 146 {
 147         struct timer8_priv *p = ced_to_priv(ced);
 148
 149         BUG_ON(!clockevent_state_oneshot(ced));
 150         timer8_set_next(p, delta - 1);
 151
 152         return 0;
 153 }
 154
 155 static struct timer8_priv timer8_priv = {
 156         .ced = {
 157                 .name = "h8300_8timer",
 158                 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 159                 .rating = 200,
 160                 .set_next_event = timer8_clock_event_next,
 161                 .set_state_shutdown = timer8_clock_event_shutdown,
 162                 .set_state_periodic = timer8_clock_event_periodic,
 163                 .set_state_oneshot = timer8_clock_event_oneshot,
 164         },
 165 };
 166
 167 static void __init h8300_8timer_init(struct device_node *node)
 168 {
 169         void __iomem *base;
 170         int irq;
 171         struct clk *clk;
 172
 173         clk = of_clk_get(node, 0);
 174         if (IS_ERR(clk)) {
 175                 pr_err("failed to get clock for clockevent\n");
 176                 return;
 177         }
 178
 179         base = of_iomap(node, 0);
 180         if (!base) {
 181                 pr_err("failed to map registers for clockevent\n");
 182                 goto free_clk;
 183         }
 184
 185         irq = irq_of_parse_and_map(node, 0);
 186         if (!irq) {
 187                 pr_err("failed to get irq for clockevent\n");
 188                 goto unmap_reg;
 189         }
 190
 191         timer8_priv.mapbase = base;
 192
 193         timer8_priv.rate = clk_get_rate(clk) / SCALE;
 194         if (!timer8_priv.rate) {
 195                 pr_err("Failed to get rate for the clocksource\n");
 196                 goto unmap_reg;
 197         }
 198
 199         if (request_irq(irq, timer8_interrupt, IRQF_TIMER,
 200                         timer8_priv.ced.name, &timer8_priv) < 0) {
 201                 pr_err("failed to request irq %d for clockevent\n", irq);
 202                 goto unmap_reg;
 203         }
 204
 205         clockevents_config_and_register(&timer8_priv.ced,
 206                                         timer8_priv.rate, 1, 0x0000ffff);
 207
 208         return;
 209 unmap_reg:
 210         iounmap(base);
 211 free_clk:
 212         clk_put(clk);
 213 }
 214
 215 CLOCKSOURCE_OF_DECLARE(h8300_8bit, "renesas,8bit-timer", h8300_8timer_init);